Project Summary The proposed study focuses on adolescent childbearing among the U.S. Hispanic/Latina (hereafter: Hispanic) population. Declines in teen fertility in the U.S have been widespread and, in recent years, have been particularly large among Hispanic/Latina adolescents. Given their disproportionate share of teen births (over one-third of all teen births in 2017 were to Hispanic teens), the drop in the Hispanic birth rate accounts for a substantial portion of the recent decline in the national teen birth rate. Beyond birth data reports, however, there has been no formal demographic accounting of these unprecedented declines that considers the vast heterogeneity and significant changes in the Hispanic population. This kind of rich description is an essential, albeit frequently bypassed, step in the broader tasks of identifying the causes (both proximate and distal) of the impressive declines in Hispanic teen fertility. We leverage nearly 30 years of Natality data (1991-2018) to first determine if declines in Hispanic teen birth rates have been widespread or exclusive to particular sub-groups (cross-classified by different combinations of region-of-origin, nativity, geographic location in the U.S., age, and marital status). Second, we employ decomposition analysis to adjudicate between different explanations (i.e. compositional shifts vs. unobserved behavioral changes) behind any documented declines. Together, our approach will reveal patterns that are essential to a more comprehensive understanding of Hispanic teen fertility, including how it has (or has not) changed and the reasons for any observed changes. By identifying sub-groups at continued teen childbearing risk and identifying the sources of observed declines, this study will help inform continuing policy and programmatic efforts focused on adolescent pregnancy prevention.